Transcripts - Population structure models

1.
Demographic Transition (Population Change)
What do you need to know?
1.
Population changes over time and space.
2. Population change can be shown on two
models.

2.
Model 1: The DTM
(Demographic Transition Model)
Stage 1
Both high birth rates and death rates fluctuate in the
first stage of the population model giving a small
population growth (shown by the small total
population graph).

3.
Model 1: The DTM
(Demographic Transition Model)
Stage 2
Birth rates remain high, but death rates fall rapidly causing a high
population growth (as shown by the total population graph).

4.
Model 1: The DTM
(Demographic Transition Model)
Stage 3
Birth rates now fall rapidly while death rates continue to fall. The total
population begins to peak and the population increase slows to a
constant.

5.
Model 1: The DTM
(Demographic Transition Model)
Stage 4
Both birth rates and death rates remain low, fluctuating with
'baby booms' and epidemics of illnesses and disease. This
results in a steady population.

6.
Model 1: The DTM
(Demographic Transition Model)
Stage 5?
A stage 5 was not originally thought of as part of the DTM, but
some northern countries are now reaching the stage where total
population is declining where birth rates have dropped below
death rates.

7.
Model 2: The PPM
(Population Pyramid Model)
The PPM - 'Population Pyramid Model' shows how dynamic
(subject to change) population is. The model is structured
to show 'snapshots' of a population at four points during
its development, which are shown as Stages 1 - 4. A
country will progress through the stages.

12.
Stage 1
Stage 2
Stage 3
Stage 4
Expansive.
Expansive.
Stationary.
Contractive.
Concave sides. Straight sides. Convex sides. Convex sides.
Still high birth Declining birth Very low birth
High birth rate.
rate.
rate.
rate.
High death
Falling death
Low death rate. Low death rate.
rate.
rate.
Short life
Slightly longer
Long life
Longer life
expectancy. life expectancy. expectancy.
expectancy.
An increasing
Rapid fall in
Fall in DR so
proportion of
Higher
each upward
more people
the population dependency
age group due
living into
is in the 65+
ratio.
to high DR.
middle age.
age group.
Niger
Haiti
Morocco
Australia
>>>>Economic development increases >>>>